Hello, I just purchased a 1990 xj6 sovereign, its in great condition doent seem to leak any oil. It's in immaculate condition inside and out. The only issue I seem to have with it is when accelerating the engine seems to loose power at around 3000 rpm.

so when gradually increasing speed i have no issues but if I hit the peddle down hard the engine gets stuck at around 3000 rpms, wont go past 3000 just sputters. let go and no issues.

Any suggestions would be appreciated

 

its starts with no problems first turn and its on and running fine

 

What engine does it have?
I would check fuel pressure first; there should be a schrader valve on the fuel rails , to which you can attach a gauge.
If that is ok, change plugs.

 

Just fixed it an hour ago. It was the ignition coil